A slide valve apparatus that is used for flow rate control when molten metal is discharged is typically provided with refractories such as a plurality of plates or a nozzle having a molten metal flow-through hole, and the cross-sectional area of the flow-through hole is changed to adjust the flow rate and close the flow-through hole by reciprocatingly moving a plate refractory, which is called a slide plate, among those refractories. In order to prevent the molten metal from leaking, a strong surface pressure is applied to the slide plate such that the slide plate is brought into intimate contact with a fixed plate which is fixed to a base frame. When the refractories attached to the apparatus, such as the plates, are inspected and replaced, this surface pressure is released and the slide valve apparatus is then opened. Where the inspection and replacement are completed, the slide valve apparatus is closed and the surface pressure is applied again for implementing the next operation. A large number of manual or automatic methods have been heretofore invented for applying/releasing the surface pressure in the above-described process.
The applicant has earlier suggested the configuration described in Patent Literature 1 as a slide valve apparatus for automatic application of surface pressure (referred to hereinbelow as SV apparatus) suitable for applying/releasing the surface pressure by moving a slide case accommodating the slide plate.
The SV apparatus described in Patent Literature 1 is provided with a surface pressure release position on the outer side of a discharge stroke, which is the movement range of the slide case during the discharge (between the fully closed position and fully open position of the flow-through hole), and the surface pressure can be automatically applied/released by reciprocatingly moving the slide case between the surface pressure release position and within the discharge stroke.
The operation of the SV apparatus described in Patent Literature 1 is described below in a simple manner.
Thus, as shown in FIGS. 22 to 26, during the usual operation, rollers 131, 132 of a slide case 4 are placed on the upper surfaces of lower sides 10b, 10b of surface pressure load members 10, 10 as shown in FIGS. 22 and 24, the slide case 4 receives an upward pushing force through the surface pressure application members 10, 10 due to the elastic force of compression springs 12, 12 and a slide plate 5 is thus pressed against a fixed plate 3 by a predetermined surface pressure.
Further, a stopper 17 is advanced and inserted between the base frame 2 and a rod connection portion 4a of the slide case 4, thereby preventing the slide case 4 from unintentionally moving to a “replacement position C”.
FIG. 24 shows a state during molten metal outflow realized when the flow-through holes 3a, 5a of the fixed plate 3 and the slide plate 5 are aligned. In order to stop the outflow of the molten metal from this state, a drive device 7 is actuated to extend a rod 7a and move the slide case 4 to a “fully closed position B”, thereby ensuring the misalignment of the flow-through holes 3a, 5a and stopping the outflow of the molten metal.
The state in which the slide plate 5 is constantly pressed by the surface pressure application members 10 against the fixed plate 3 under the predetermined surface pressure is maintained even when the slide plate 5 moves from a “fully open position A” to a “fully closed position B”, thereby preventing the leak of steel and introduction of air.
Further, where a chute nozzle 6 or the slide plate 5 is damaged by melting, it is replaced, and in such a case, the stopper 17 is initially moved back and pulled out from between the base frame 2 and the rod connection portion 4a of the slide case 4, and then the rod 7a of the drive device 7 is shortened and the slide case 4 is moved to the “replacement position C”.
Where the replacement position C is reached, the rollers 131, 132 of the slide case 4 escape to the outside from an end 10c and a notch 14 of the lower sides 10b, 10b of the surface pressure application members 10, 10 respectively. As a result, the slide case 4 can be turned outwardly about a shaft 15, as shown in FIG. 26, and after the slide case 4 has been turned to the outside, the slide plate 5 and the chute nozzle 6 are pulled out, new chute nozzle and slide plate are set, and the slide case 4 can be returned to the operation state by pushing the rollers 131, 132 in to the level of the upper surface of the lower side 10b of the surface pressure application member 10 and then extending the rod 7a of the drive device 7.
The stopper 17 is then moved forward and introduced between the base frame 2 and the slide case 4 side, and subsequent operations are started.
Patent Literature 1: Japanese Patent No. 4,216,422